How the strong segmentation of cascade reservoir dams and the spatiotemporal changes of sediment retention volume affect the river morphology adjustment in the reservoir area is a scientific issue worthy of exploratio...How the strong segmentation of cascade reservoir dams and the spatiotemporal changes of sediment retention volume affect the river morphology adjustment in the reservoir area is a scientific issue worthy of exploration.This study aims to reveal the adjustment mechanism of the thalweg longitudinal profile of cascade reservoirs.This study focuses on the Xiangjiaba and Xiluodu reservoirs located in the lower reaches of the Jinsha River.Utilizing multi-period observational data of thalweg elevation in reservoir reaches both before and after dam construction,the research employs statistical,geomorphological,and sedimentological methodologies to analyze variation characteristics in the measured curves,trend curves,and theoretical fitting curves of the thalweg longitudinal profile.The investigation ultimately reveals two distinct adjustment patterns in the longitudinal profiles of these cascade reservoirs:the concave curve type and the convex curve type.The former is characterized by weak riverbed scouring and silting changed to rapid aggradation in the upstream section of the reservoir area after dam closure,then changed to slow aggradation in the whole reservoir area,which is the common feature of reservoirs that were built earlier and are relatively located in the downstream(such as the Xiangjiaba Reservoir).The latter is characterized by a straight line or concave curve type with weak riverbed scouring and silting before the dam closure changed to a convex curve type with strong siltation after dam closure,which is the characteristic of reservoirs that were built later and are relatively located in the upstream(such as the Xiluodu Reservoir).The adjustment of the cascade reservoir longitudinal profile is controlled by the spatiotemporal changes of the sediment deposition volume and sedimentation rate in the reservoir area,and the alternating changes of the hydrodynamic gradient and regulation mode affect the spatial heterogeneity of the sedimentation rate.The research results are helpful for understanding the adjustment mechanism of the cascade reservoir longitudinal profile in similar areas and have a guiding role in predicting the adjustment trend of the cascade reservoir longitudinal profile without observation data.展开更多
Heavy rain falling on land at the upper reaches of the Kelantan River, Malaysia, on December 2014, had resulted in severe soil erosion and untold damages to croplands. The lower reaches of the river were heavily silte...Heavy rain falling on land at the upper reaches of the Kelantan River, Malaysia, on December 2014, had resulted in severe soil erosion and untold damages to croplands. The lower reaches of the river were heavily silted with infertile materials considered unfit for crop production. A study was conducted to explain why the flood phenomenon occurred, to determine the physico-chemical properties of the sediments silted in the Kelantan Plains and to propose measures for soil mitigation. Results showed that the silted sediments were characterized by the presence of quarts, mica, feldspars, kaolinite, gibbsite and hematite believed to come from the top- and subsoil of the upland areas. The sediments’ pH was very low and Al and/or Fe contents were very high, while nitrogen and carbon contents varied from area to area. Soils in the Kelantan Plains badly affected by this great flood needed to undergo proper ameliorative program. The most appropriate measure would be to apply ground magnesium limestone in combination with bio-fertilizer fortified with beneficial microbes that would increase their pH to a level above 5, which consequently eliminates Al<sup>3+</sup> and/or Fe<sup>2+</sup> that causes toxicity to the crops growing on them. The organic material so added would enhance the formation of soil structures. It is advised that the farming communities in the upper reaches of the Kelantan River would have to follow the advice advocated by the Department of Agriculture, Peninsular Malaysia, via MyGAP initiative, in order to sustain agricultural production on their land.展开更多
In this paper, silt sediment is considered to be Bingham body, which is made up of coarse and fine particles in front of a hydraulic gate. The coarse and fine particles provide friction and shear stress in the course ...In this paper, silt sediment is considered to be Bingham body, which is made up of coarse and fine particles in front of a hydraulic gate. The coarse and fine particles provide friction and shear stress in the course of opening the gate. They constitute together the adhesion force of the sediment. Based on this viewpoint, this paper puts forward a formula for the effect of silt sediment on the lifting force. The formula includes gate weight, down-suction force, sealing rubber friction, plus-weight, water-column pressure, plus-silted-sediment weight and rolling(or sliding)-bearing friction. Finally, the verification results show that the formula has certain reliability and the calculation accuracy can meet the need of practical engineering.展开更多
An initial-boundary value problem for shallow equation system consisting of water dynamics equations,silt transport equation, the equation of bottom topography change,and of some boundary and initial conditions is stu...An initial-boundary value problem for shallow equation system consisting of water dynamics equations,silt transport equation, the equation of bottom topography change,and of some boundary and initial conditions is studied, the existence of its generalized solution and semidiscrete mixed finite element(MFE) solution was discussed, and the error estimates of the semidiscrete MFE solution was derived.The error estimates are optimal.展开更多
基金National Key R&D Program of China,No.2022YFC3203903National Natural Science Foundation of China,No.42371010,No.41971004。
文摘How the strong segmentation of cascade reservoir dams and the spatiotemporal changes of sediment retention volume affect the river morphology adjustment in the reservoir area is a scientific issue worthy of exploration.This study aims to reveal the adjustment mechanism of the thalweg longitudinal profile of cascade reservoirs.This study focuses on the Xiangjiaba and Xiluodu reservoirs located in the lower reaches of the Jinsha River.Utilizing multi-period observational data of thalweg elevation in reservoir reaches both before and after dam construction,the research employs statistical,geomorphological,and sedimentological methodologies to analyze variation characteristics in the measured curves,trend curves,and theoretical fitting curves of the thalweg longitudinal profile.The investigation ultimately reveals two distinct adjustment patterns in the longitudinal profiles of these cascade reservoirs:the concave curve type and the convex curve type.The former is characterized by weak riverbed scouring and silting changed to rapid aggradation in the upstream section of the reservoir area after dam closure,then changed to slow aggradation in the whole reservoir area,which is the common feature of reservoirs that were built earlier and are relatively located in the downstream(such as the Xiangjiaba Reservoir).The latter is characterized by a straight line or concave curve type with weak riverbed scouring and silting before the dam closure changed to a convex curve type with strong siltation after dam closure,which is the characteristic of reservoirs that were built later and are relatively located in the upstream(such as the Xiluodu Reservoir).The adjustment of the cascade reservoir longitudinal profile is controlled by the spatiotemporal changes of the sediment deposition volume and sedimentation rate in the reservoir area,and the alternating changes of the hydrodynamic gradient and regulation mode affect the spatial heterogeneity of the sedimentation rate.The research results are helpful for understanding the adjustment mechanism of the cascade reservoir longitudinal profile in similar areas and have a guiding role in predicting the adjustment trend of the cascade reservoir longitudinal profile without observation data.
文摘Heavy rain falling on land at the upper reaches of the Kelantan River, Malaysia, on December 2014, had resulted in severe soil erosion and untold damages to croplands. The lower reaches of the river were heavily silted with infertile materials considered unfit for crop production. A study was conducted to explain why the flood phenomenon occurred, to determine the physico-chemical properties of the sediments silted in the Kelantan Plains and to propose measures for soil mitigation. Results showed that the silted sediments were characterized by the presence of quarts, mica, feldspars, kaolinite, gibbsite and hematite believed to come from the top- and subsoil of the upland areas. The sediments’ pH was very low and Al and/or Fe contents were very high, while nitrogen and carbon contents varied from area to area. Soils in the Kelantan Plains badly affected by this great flood needed to undergo proper ameliorative program. The most appropriate measure would be to apply ground magnesium limestone in combination with bio-fertilizer fortified with beneficial microbes that would increase their pH to a level above 5, which consequently eliminates Al<sup>3+</sup> and/or Fe<sup>2+</sup> that causes toxicity to the crops growing on them. The organic material so added would enhance the formation of soil structures. It is advised that the farming communities in the upper reaches of the Kelantan River would have to follow the advice advocated by the Department of Agriculture, Peninsular Malaysia, via MyGAP initiative, in order to sustain agricultural production on their land.
基金Supported by Shandong Province Outstanding Young Scientist Award Fund(No.BS2014SF016)the National Natural Science Foundation of China(No.50979067)+1 种基金Ludong University Doctor Introduction Foundation(No.LY2014026 and No.LY2014028)the Open Research Fund Program of State Key Laboratory of Water Resources and Hydropower Engineering Science(No.2012B104)
文摘In this paper, silt sediment is considered to be Bingham body, which is made up of coarse and fine particles in front of a hydraulic gate. The coarse and fine particles provide friction and shear stress in the course of opening the gate. They constitute together the adhesion force of the sediment. Based on this viewpoint, this paper puts forward a formula for the effect of silt sediment on the lifting force. The formula includes gate weight, down-suction force, sealing rubber friction, plus-weight, water-column pressure, plus-silted-sediment weight and rolling(or sliding)-bearing friction. Finally, the verification results show that the formula has certain reliability and the calculation accuracy can meet the need of practical engineering.
文摘An initial-boundary value problem for shallow equation system consisting of water dynamics equations,silt transport equation, the equation of bottom topography change,and of some boundary and initial conditions is studied, the existence of its generalized solution and semidiscrete mixed finite element(MFE) solution was discussed, and the error estimates of the semidiscrete MFE solution was derived.The error estimates are optimal.
